Computationally efficient smart antennas for CDMA wireless communications

Abstract

Abstract-The analysis in this paper concerns the performance of smart antenna algorithms when used in code-division multiple access (CDMA) wireless communication systems. Complex pseudonoise (PN) spreading, despreading, and pilot-aided channel estimates in the cdma2000 reverse link are some of major characteristics that are different from those in the IS-95 CDMA systems. These different features are included in our analysis. Four computationally efficient smart antenna algorithms are introduced: 1) smart antenna based on maximum output power criteria without lagrange multiplier; 2) smart antenna based on maximum signal-to-interference-plus-noise output power ratio (SINR) criteria with eigenvector solution; 3) smart antenna based on maximum SINR output criteria without eigenvector solution; 4) more simplified smart antenna based on maximum SINR output criteria without eigenvector solution. Algorithms (1) and (4) require only 4 computational instruction cycles per snapshot where is the number of antenna array elements. Algorithms (2) and (3) require 2 and (4 + 2 2 ) operations per snapshot, respectively. These computational loads are significantly smaller than those of typical eigenvalue decomposition blind detection approaches. Bit error rates (BERs) resulting from these algorithms are evaluated through simulation. Double spike power delay profile with equal or unequal power is used. Also, a cluster of interfering users and scattered interference users are considered. For BER comparisons, antenna diversity using equal gain combining is also analyzed. The four smart antenna algorithms show significant capacity improvement compared to the antenna array diversity using equal gain combining under the double spike power delay profile with equal power and scattered interference environments.Index Terms-Adaptive array antenna, code division multiple access (CDMA), mobile fading environment, multiple access interference, smart antenna, wireless communications.

Effect of Mutual Coupling on the Interference Rejection Capabilities of Linear and Circular Arrays in CDMA Systems

“…In the context of CDMA systems, many research papers have addressed the SIR improvement in passing only, while also neglecting mutual coupling between antenna elements [3], [5]- [7]. The applications of the spatial interference suppression coefficient have cropped up in a number of recent papers and are mainly concerned with finding the mean value, e.g., in [8], where it is employed in determining an expression for the theoretical bit error rate of a smart antenna system, and in [9] and [10], where it is used to find the capacity of a multiantenna system for CDMA.…”

Pn Code Acquisition Using Smart Antenna and Adaptive Thresholding Cfar Based on Ordered Data Variability for Cdma Communications

“…The complex equivalent baseband signal V m (t) at the input of the correlator for the mth element can be written as [26] …”

Design of Phased Antenna Arrays using Evolutionary Optimization Techniques

“…Among antenna array configurations, the phased linear array is the most common form employed in cellular and personal communication systems (PCS) (Song et al, 2001). However, 360° scanning of the radiation beam can be obtained by combining a few linear arrays whose sector scans add to give the desired 360° scan.…”